Image-forming composition and a process of making it



Patented Mar. 13, 1951 IMAGE-FOBMIN G COMPOSITION AND A PROCESS OF MAKING IT Charles; Van Dusen, Jr., Willoughby, Ohio, as-

s gnor to AddressographsMul-tigraph Corporar tlon, W mi gt n. D L, a corporat n of Dela- Wa t}.

N'o Drawing. Application February 5, 1947, Serial No. $26,737

5. Gl' msl- 19 This invent on relates to planographic printing. More specifically, this invention relates to an oily wax-free image-forming composition WhlCh contains a fatty acid component and is especially adapted for use upon typewriter ribwith the new image-forming composition; and to a method of preparing th new image-forming composition and the said. typewriter ribbon impregnated therewith.

" One of the difficulties sometimes encountered [in the use of typewriter ribbon image-forming- .compositions, containing a fatty acid component but free from carbon black, has been the tendency of such image-forming compositions to spread, upon standing, after application to a planographic printng platemaster, and particularly when used upon parchment and like cellulose planographic printing plate masters. This tendency to spread has been particularly noticeable in those instances in which, part of the message to be carried by such a cellulose base planographic master printing plate has. been applied ortyped on the plate at one time and the remainder of the image typed thereon at a later I date, such for example, as on the following day. ,I-Ience it has been customary heretofore in the 1 art to employ carbon black in such image-forming compositions to prevent objectionablespreadin g thereof, as aforesaid.

In the practice of the presentinVention I have 1 found that a satiiactory image-forming composition conta ning a fatty acid component and I substantially free from any tendency to spread .1s afforded the fatty acid component of the new iInageriQrming composition. is controlledand "maintained within certain critical limits, herei imiter sp c fi d. lThus. I have found that th newfimage-forming composition is substantially I free from tendency to spread after application to a parchment or like cellulose base pianora printin plate master. More sp c fi ally, have found that if. the preierred fatty acid :,-component r r the new image-firming composi- .tion, namely, stearic acid, is maintained within critical limits of not ,substantialiy less than two per cent .(2%) nor substantially more four per cent (4 by weight, of the new image-forming composition, the resulting image-forming composition is substantially ,free of vany'tendency to spread upon standing, after it has b en pplie to apartment or like cellulose base planographic printing plate master, and that a superior fatty acid-containing typewriter ribbon image-forming composition is thus afforded without the necessity for employing any, carbon black therein to prevent image spread.

Moreover, I have found that if certain s'lected papers are impregnated with the new imageforming composition, a satisfactory typewriter ribbon vfor writing upon cellulose planographio printing plates is afforded,

Accordingly, an object, of the present invention is to afford a. new and improved imageormin mposition which has th de rable properties and characteristics herfin specified and others which are inherent therein.

An additional object of the invention is to provide a novel paper base typewriter ribbon impregnated with the new image-forming .composition in and for use in writing upon cellulose planographic printing plates employed in direct image reproduction.

A further object of the invention is to provide a novel method of preparing the new imageforming composition.

A typical formula which may be iollowed in preparing the new image-forming composition is shown in the following example in which all parts indicated are by weight:

Example- Per cent by weight (1) Image-forming material (nigrosin base black dye) ap 27 (2) 'Tricresyl phosphate (solvent for the nigrosine base dye) (3) (Diluent) diethylene glycol monolaurate -.V--.-V-V--V--- 20 (4) Steario acid 3 In preparing the new image-forming composition according to the formula set forth in the foregoing example, a variation oi about 2 per cent from the percentages stated, either more or=1ess,

in the solvent (tricresyl phosphate) and in the oi the comp s tion are thorough mixed together with constant stirring. The diluent, namely, the diethylene glycol mono-laurate and the stearic acid, in finely divided form, are then added to the mixture which is then heated gradually to a temperature of about 125 C. and maintained at this temperature for about five hours,

with constant stirring, so as to effect a substantially permanent solution of the stearic acid in the composition. The composition is then allowed to cool gradually to atmospheric temperature with constant stirring.

The resulting product is a free-flowing oily fluid image-forming composition containing a fatty acid component, but substantially free of carbon black, which is then ready for use in impregnating a suitable paper base, such as that hereinafter described, in making the new paper base typewriter ribbon. The preferred viscosity of the new image-forming composition, prepared as aforesaid, is not substantially less than 15,000 centipoises at a temperature of 23 C.

In preparing the new image-forming composition, as aforesaid, the stearic acid component thereof may be added in any suitable form such. for example, as a lump of stearic acid or in finely divided form since it readily dissolves in the mixture at the aforesaid temperature of about 125 C. preferably employed during the mixing operation since that temperature is approximately the melting point of the stearic acid (125 0.). However, the best results are obtained by employing stearic acid in the form of lumps, with the mixture at a temperature of about 125 C. and by incorporating the various components of the composition in the order stated since this facilitates putting the materials into solution and prevents the formation of lumps of undissolved stearic acid in the resulting composition.

It has been found in the use of the new imageforming composition that the incorporation therein of the stearic acid component thereof within the critical limits specified effectively prevents objectionable spreading of the new imageforming composition after it has been applied from a typewriter ribbon impregnated therewith to a parchment or like cellulose base planographic printing plate master and the latter allowed to stand as, for example, between the time when part of the message to be carried by the plate is typed thereon on one day and the remainder typed thereon on a subsequent day. Hence, a difficulty sometimes experienced in prior image forming compositions containing a fatty acid component but without carbon black is avoided and a new and improved fatty acid-containing image-forming composition is afforded without the need for, or inclusion therein of, any carbon able or equivalent image-forming materials in the form of organic dyes or the like, which are soluble in the tricresyl phosphate solvent, or other suitable solvent, may be employed in place of the nigrosine base black dye used in the foregoing example, without departing from the scope and contemplation of the present invention.

I have found that selected cellulosic materials or papers may be employed as the base of a typewriter ribbon impregnated with the new image-forming composition and among these are the paper known as Superflex (Manning Paper Co.) which is made of used rope stock and the paper known as Special Aldex C (Aldine Paper 00.). Either of these'papers impregnated with the new image-forming composition and cut to proper length and width may be employed as the base of the new typewriter ribbon for writing upon cellulose base planographic printing plates.

It will thus be seen from the foregoing description that the present invention accomplishes its intended objects, and that the new fatty acid image-forming composition and the paper base typewriter ribbon impregnated therewith which are provided by the present invention have the desirable advantages and characteristics and accomplish their intended objects, including those hereinbefore specifically pointed out and others which are inherent in the invention.

I claim:

1. An image-forming composition which is especially adapted for use in forming direct images upon planographic printing plates, said image-forming composition consisting of a solution of a nigrosine base black dye in tricresyl phosphate glycol mono-laurate as a diluent, and containing stearic acid introduced into the composition as an initial ingredient thereof in an amount not substantially less than two per cent nor substantially more than four per cent of the composition, by weight, said image-forming composition being substantially free of carbon black.

2. The method of preparing an image-forming composition for use in forming images upon planographic printing plates by the direct image method, said method comprising dissolving a nigrosine base black dye in tricresyl phosphate, intimately mixing finely divided stearic acid in the mixture thus prepared and in an amount not substantially less than two per cent nor substantially more than four per cent of the composition, by weight, heating the resulting mixture while constantly stirring it, to a temperature of about 125 C. and maintaining it at this temperature for a period of about five hours, and then allowing the mixture to cool gradually to atmospheric temperature, with constant stirring.

. an amount not substantially less than two per cent nor substantially more than four per cent of the composition, by weight, heating the resulting mixture while constantly stirring it, to a temperature of about C. and maintaining it at this temperature for a period of about five hours, and then allowing the mixture to cool gradually to atmospheric temperature, with constant stirring.

4. The method of preparing an image-forming composition for use in writing images upon planographic printing plates by the direct image method which comprises dissolving a nigrosine base black dye in a mixture of tricresyl phosphate and diethylene glycol mono-laurate, intimately mixing finely divided stearic acid in the mixture thus prepared and in an amount not substantially less than two per cent nor substantially more than four per cent of the composition, by weight, heating the resulting mixture while constantly stirring it, to a temperature of about 125 C. and maintaining it at this temperature for a period of about five hours, and

then allowing the mixture to cool gradually to atmospheric temperature, with constant stirring.

CHARLES H. VAN DUSEN, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 437,780 Higgins Oct. 7, 1890 1,487,873 Marston Mar. 25,- 1924 1,688,117 Davis Oct. 16, 1928 Number 10 Number OTHER REFERENCES Ellis: Printing Inks (1940), pages 416 and 

1. AN IMAGE-FORMING COMPOSITION WHICH IS ESPECIALLY ADAPTED FOR USE IN FORMED DIRECT IMAGES UPON PLANOGRAPHIC PRINTING PLATES, SAID IMAGE-FORMING COMPOSITION CONSISTING OF A SOLUTION OF A NIGROSINE BASE BLACK DYE IN TRICRESYL PHOSPHATE GLYCOL MONO-LAURATE AS A DILUENT, AND CONTAINING STEARIC ACID INTROUDCED INTO THE COMPOSITION AS AN INITIAL INGREDIENT THEREOF IN AN AMOUNT NOT SUBSTANTIALLY LESS THAN TWO PER CENT NOR SUBSTANTIALLY MOER THAN FOUR PER CENT OF THE COMPOSITION, BY WEIGHT, SAID IMAGE-FORMING COMPOSITION BEING SUBSTANTIALLY FREE OF CARBON BLACK. 